检索结果-南通市图书馆

Amphibian and reptilian distribution patterns in the transitional zone between the Euro-Siberian and Central Asia Subrealms

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2015年第4期7卷 555-565页

作者： ZHOU Lu SHI lei College of Animal Science Xinjiang Agricultural University

There exist some controversies over the larger zoogeographic divisions of the arid areas of Central Asia, whose characteristics include complex ecological environments, complex fauna origins and unique patterns of animal distribution. The aim of this study was to determine, using quantitative analysis, the distribution patterns of amphibians and reptiles in the arid areas of Central Asia, whose various physiographical regions were divided into 17 Operative Geographical Units （OGUs）. Based on the presence or absence of 52 amphibian and reptile genera in the 17 OGUs, and by making use of the Czekanowski Similarity Index, the Baroni-Urbani and Buser＇s Similarity Index, and the strong and weak boundary test, we studied the biotic boundaries within these contested regions. In accordance with our results, the classification dendrogram was divided into two main branches. One branch is composed of the northern OGUs of the Altai Mountains which are a part of the Euro-Siberian Subrealm. The other branch includes all of the OGUs south of the Altai Mountains, which belong to the Central Asia Subrealm. There is a significantly weak biotic boundary （DW〉0, GW〉GS, P〈0.01） between the Euro-Siberian Subrealm and the Central Asia Subrealm that corre- sponded to the transitional zones. The boundary between the two subrealms runs along the Altai Mountains, the Sayan Mountains, the Hangai Mountains and the Mongolian Dagurr Mountains. The boundaries between the main branches in the Central Asia Subrealm are weak, reflecting the widespread existence of transitional zones in the arid areas of Central Asia. The Tianshan Mountains should be elevated to form its own separate region, ＂the Middle Asian Mountain Region＂, which, due to its special fauna and environment, would be classified at the same level as the Mongolia-Xinjiang Region. With the approach of creating a cluster analysis dendogram based upon the genera of amphibians and reptiles, the relationship of these higher level zoogeographi

关键词： amphibian and reptile distribution pattern higher level zoogeographic division similarity analysis boundary test arid area Central Asia

High performance n^+p-Si/Ti/NiS_xO_y photocathode for photoelectrochemical hydrogen evolution in alkaline solution

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2019年第3期28卷 101-107页

作者： Qing Jia Chunlin yu Wei Liu Guokui Zheng Chaojun lei Lecheng lei Xingwang Zhang Key Laboratory of Biomass Chemical Engineering of Ministry of Education College of Chemical and Biological Engineering Zhejiang University

Silicon, as a promising semiconductor for fabricating photocathode toward photoelectrochemical hydrogen evolution reaction(PEC-HER), should be improved in light harvesting ability and catalytic kinetics to obtain high PEC performance. Herein, a novel amorphous Nickel Oxysulfide(NiS_xO_y) film is effectively integrated with a Ti protected n^+p-Si micropyramid photocathode by the electrodeposition method. The fabricated n^+p-Si/Ti/Ni SxOyphotocathode exhibits excellent PEC-HER performance with an onset potential of 0.5 V(at J =-0.1 mA/cm^2), a photocurrent density of-26 mA/cm^2 at 0 V vs. RHE, and long term stability of six hours in alkaline solution(pH ≈ 14). The synergy of unique n^+p-Si micropyramid architectures(omnidirectional broadband light harvesting ability), novel amorphous NiS_xO_y catalyst(high HER electrocatalytic activity and good optical transparency) results in the high performance of n^+pSi/Ti/Ni S_xO_y. This work offers a novel strategy for effectively integrating electrocatalysts with semiconductor to design efficient photoelectrode toward PEC water splitting.

关键词： Photoelectrochemical water splitting Silicon Photocathode Nickel oxysulfide

Growth of certain harmonic functions in an n-dimensional cone

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2013年第4期8卷 891-905页

作者： lei QIAO Guantie DEng Department of Mathematics and Information Science Henan University of Economics and Law Zhengzhou 450002 China School of Mathematical Science Beijing Normal University Laboratory of Mathematics and Complex Systems Ministry of Education Beijing 100875 China

We give the growth properties of harmonic functions at infinity in a cone, which generalize the results obtained by Siegel-Talvila.

关键词： Growth property harmonic function cone

The deformation of Poincar subgroups concerning very special relativity

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2014年第5期57卷 859-874页

作者： ZHAng lei XUE Xun Institute of Theoretical Physics Department of PhysicsEast China Normal University Kavli Institute for Theoretical Physics China at the Chinese Academy of Sciences

We investigate here various kinds of semi-product subgroups of Poincar6 group in the scheme of Cohen-Glashow＇s very special relativity along the deformation approach by Gibbons- Gomis-Pope. For each proper Poincar6 subgroup which is a semi-product of proper lorentz group with the spacetime translation group T（4）, we investigate all possible deformations and obtain all the possible natural representations inherited from the 5 - d representation of Poincar6 group. We find from the obtained natural representation that rotation operation may have additional accompanied scale transformation when the original Lorentz subgroup is deformed and the boost operation gets the additional accompanied scale transformation in all the deformation cases. The additional accompanied scale transformation has a strong constrain on the possible invariant metric function of the corresponding geometry and the field theories in the spacetime with the corresponding geometry.

关键词： very special relativity deformation of Poincare subgroups natural representation accompanied scale transformation

Geochemistry and Petrogenesis of the ca. 2.5Ga High-K Granitoids in the Southern North China Craton

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2019年第3期30卷 647-665页

作者： lei Li Wenjian Zhai State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences China University of Geosciences Wuhan 430074 China No.1 Geology and Mineral Resources Survey Institute of Henan Geology and Mineral Exploration and Development Bureau Luoyang 471023 China Henan Institute of Geological Survey Zhengzhou 450001 China

Archean high-K granitoids, generally formed after tonalite-trondhjemite-granodiorite (TTGs), are important for understanding crustal reworking of ancient cratons. The Linshan Archean high-K granitoids from the southern Trans-North China Orogen (TNCO) provide a window into the conti-nental crustal evolution of the North China Craton (NCC). They mainly consist of monzogranite and granodiorite which were formed during 2 542-2 503 Ma. The high-K granitoids have high SiO2 (65.86wt.%-78.08wt.%), K2O (3.29 wt.%-7.62wt.%) and low P2O5 (0.01 wt.%-0.27wt.%). They display right inclined REE patterns with negative Eu anomalies (Eu/Eu*=0.20-0.81).Their spider diagram is characterized by enrichment of Rb, K, Th, U and depletion of Nb, Ta, Zr, Ti. The rocks have positive and variable zircon εHf(t)(+2.5 to +6.6) and whole-rock εHf(t)(+0.7 to +4.5) with two-stage model ages (TDM2^Hf=2.87-2.64 Ga;TDM2^Nd=2.77-2.50 Ga) similar to those of the Archean TTG-ty pe rocks, amphibolites and diorites in the area. These evidences suggest that the high-K granitoids were produced by partial melting of juvenile crustal rocks. The Linshan high-K granitoids show relatively high whole-rock zircon saturation tempera-tures (694-889℃) and low Sr/y ratios (0.27-21.1), indicating low pressure partial melting. Combined with other geological evidences, the Linshan high-K granitoids are suggested to have been produced by partial melting of the continental crust in a post-collision extensional environment after an arc-continent collision. Thus, the NCC did not amalgamate together until ca. 2.5 Ga. Compiled zircon U-Pb ages and Hf isotopes reveal that the ca. 2.5 Ga magmatism represents reworking of the continental crust.

关键词： granitoids petrogenesis Neoarchean North China Craton

Toward qualification of additively manufactured metal parts:Tensile and fatigue properties of selective laser melted Inconel 718 evaluated using miniature specimens

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第2期97卷 239-253页

作者： H.y.Wan W.K.y.ng L.y.Wang Z.J.Zhou C.P.Li G.F.Chen L.M.lei G.P.Zhang Sheny.ng National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Materials&Manufacturing Qualification Group Corporate TechnologySiemens Ltd.Beijing 100102China AECC Shanghai Commercial Aircraft Engine Manufacturing Co. LtdShanghai 201306China

Combined with the topology optimization,additive manufacturing can be used to fabricate metal parts with complex ***,due to the geometrical variations and microstructure heterogeneities of the additively manufactured metal parts,new standards with the use of miniature specimens are required for the evalutation of the spatial distribution of mechanical properties throughout the ***,we conduct a systematic investigation on tensile and fatigue properties of selective laser melted Inconel718 specimens with different thicknesses ranging from 0.1 mm to 1 mm.A“microstructure unit”that can well reflect the microstructure characteristic of selective laser melted materials is *** results reveal that premature necking with a dramatic drop in uniform elongation occurs if the ratio(t/d)of specimen thickness(t)to the"microstructure unit"size(d)is less than *** necking is mainly attributed to the transition of strain localization *** also propose a probabilistic statistical model for fatigue limit prediction based on the available fatigue *** is recommended that the criterion of t/d≥4 should be satisfied to ensure that the yield strength,the uniform elongation,and the fatigue limit determined by the miniature specimens are comparable with those determined by standard *** findings may provdie a guide to the establishment of miniature specimen-based standards toward the qualification of additively manufactured metal parts.

关键词： Selective laser melting Inconel 718 Miniature specimen Microstructure unit Thickness effect

Optimal integrability of some system of integral equations

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2014年第1期9卷 81-91页

作者： yutian lei Chao MA Institute of Mathematics School of Mathematical Sciences Nanjing Normal UniversityNanjing 210023 China Depar(ment of Mathematics University of Colorado at Boulder Boulder CO 80309 USA

We obtain the optimal integrability for positive solutions of the Euler-Lagrange system of the weighted Hardy-Littlewood-Sobolev inequality in R^n ：{u（x）=1/｜x｜^α｜∫R^n v（y）^q｜y｜^β｜x-y｜^λdy,v（x）=1/｜x｜^β∫R^n u（y）^p｜y｜^α｜x-y｜^λdy.C. Jin and C. Li [Calc. Var. Partial Differential Equations, 2006, 26： 447-457] developed some very interesting method for regularity lifting and obtained the optimal integrability for p, q 〉 1. Here, based on some new observations, we overcome the difficulty there, and derive the optimal integrability for the case of p, q ≥1 and pq ≠1. This integrability plays a key role in estimating the asymptotic behavior of positive solutions when ｜x｜ →0 and when ｜x｜→∞.

关键词： Integral equation weighted Hardy-Littlewood-Sobolev inequality integrability interval

How cooperation arises from rational players?

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2013年第11期56卷 247-255页

作者： MU yiFen GUO lei Institute of Systems Science Academy of Mathematics and Systems ScienceChinese Academy of Sciences

In classical control systems,the plant to be controlled does not have intention to gain its payof or benefit,which is obviously not the case in various aspects of social and economic systems(or subsystems).In the latter case,competition and cooperation between players who will optimize their own payofs turn out to be an important feature,and a fundamental problem is how to achieve cooperation from these rational *** this paper,we present a neat way to lead to cooperation in dynamical Prisoner’s Dilemma *** our scenario,the two players are heterogenous with hierarchical roles as the‘leader’and the‘follower’*** is shown that the system will co-evolve into and stay at the cooperation state if and only if the leader is restricted not to take the dominating *** the special case of 1-step-memory,the optimal strategies for the leader and follower are‘Tit for Tat’and‘ALL C’*** this framework,both the heterogeneity of the players’roles and the multiplicity of time-scales are crucial for cooperation,which are quite natural settings from the view point of control ***,the boundary for cooperation also turns out to depend on the relative payofs of the players.

关键词： cooperation Prisoner’s Dilemma leader-follower game finite-memory strategy optimization

Boundedness of semilinear Duffing equations with singularity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2014年第6期9卷 1427-1452页

作者： Xiumei XIng lei JIAO School of Mathematics and Statistics YiLi Normal University Yining 835000 China School of Science Nanjing University of Science and Technology Nanjing 210094 China

We prove the boundedness of all solutions for the equation x＂＋ V＇（x） = DxG（x,t）, where V（x） is of singular potential, i.e., limx→-1 y（x） = ∞, and G（x, t） is bounded and periodic in t. We give sufficien... 详细信息

关键词： Hamiltonian system repulsive singularity boundedness ofsolutions canonical transformation Moser's small twist theorem